1. Field of the Invention
The present invention relates to an apparatus for correcting positional deviation of the light source emitting light beams in an image recording apparatus and, more particularly, to an apparatus for correcting positional deviation of the light source emitting light beams in an image recording apparatus configured to prevent occurrence of variation in dimensions of an image (hereinafter, briefly called "image size") on the photosensitive member in the main scanning direction and in the sub-scanning direction.
2. Description of the Related Art
There is an image recording apparatus which has an array of two-dimensional surface light emitting devices disposed in confrontation with a photosensitive drum through an optical system and allows the light emitting devices of the array of two-dimensional surface light emitting devices to be individually driven in accordance with an image signal, so that light beams corresponding to the image signal are emitted from the light emitting devices and the photosensitive drum rotating in the sub-scanning direction is scanned by the emitted light beams through the optical system and exposed to the same and, thereby, an electrostatic latent image is formed on the photosensitive drum. Such an image recording apparatus has come to be paid attention as the one capable of carrying out high quality and high density image recording at high speeds.
In such an image recording apparatus, need for using a polygon mirror for deflecting the light beams in the main scanning direction can be eliminated and, hence, high speed image recording can be attained. Further, by achieving high-density arrangement of the light emitting devices in the array of two-dimensional surface light emitting devices and devising a better optical system, it is expected that higher quality and higher density of the recorded image will become obtainable.
However, according to the conventional image recording apparatus, since the array of two-dimensional surface light emitting devices, optical system, photosensitive drum, and the like are fixed within a housing, when they are subjected to external vibration or temperature change, physical distortions are produced on them, whereby the positions of the beam spots produced on the photosensitive drum are deviated and the quality of the image is deteriorated. Especially when the array of two-dimensional surface light emitting devices is shifted in the direction of the optical axis or in another direction or it is tilted in a certain direction, all the light emitting devices are deviated from their right positions. Accordingly, the size of the image on the photosensitive drum in the main scanning direction and sub-scanning direction is varied and the quality of the image is deteriorated. In such a case, light emitting devices located at the extreme ends on both sides of the array of two-dimensional surface light emitting devices are greatly affected and their positional deviations put together changes the image size considerably.